Spark plug shield



Jan. 22, 1935 R. L. SHUMAKER SPARK PLUG SHIELD Original Filed July 7. 1931 iiiii -n ATTORNEYS INVENTOR Patented Jan. 193s r 1,988,859

UNITED STATES PATENTVOFFICE laymondhshumskenxenigohio application July I; 1981, Serial No. 540,208. Divided and this application June 6, 1938, Serial No. 674,557

17 Claims. (Cl. its-1m (Granted under the act of March I, 1888, as amended April 30, 1928; 370 O. G. 757) The invention described herein may be manu- The invention is further characterized by proiactured and used by or for the Government for vldins shielding means adapted for ready tgovernmental purposes, without the payment to tachment to or detachment from a spark plug me of any royalty thereon. I which is so constructed and arranged, that ac- The present invention relates generally to u atio depos ts of any substance or maelectrical apparatus and more particularly t m-l upon the insulated portion of h p s apparatus adapted for use in connection with which may be a conductor ofclectric currents electric currents which are intermittent in charis substantially P evented.

m and/or in which th intensity th ur- A further object of the present invention is 1 rent ehgnges rapidly, to DiOVldG shielding means 0! this character 11; 1 round t t h t current changes comprising a metallic sleeve which is held in rapidly in character or is intermittent, for'exgood electric contact with the ground portion ample, in an ignition system for an internal 0f h PM pl s and being provided with an combustion engine that, as a result of the elecinsulator on its inner surface, essentially a heat"v trlcal field set up by the high tension circuit resisting sleeve of insulating material of high and the spark discharge of the spark plugs dielectric strength having intimate contact with and/or magneto, electrostatic or electromagnetic the inner wall of the metallic sleeve to provide waves are propagated in the atmosphere surfor maximum heat conductivity from the heated rounding the system to such an extent as to end of the plug.

s create considerable interference with proper re- A further object of the present invention is ception in radio communication in apparatus to so arrange the insulating material that thethat is in the vicinity of the ignition system. p e etween the inner wall of the metallic The high tension ignition systems essential'ln sleeve and the surface of the terminal portion engines, particularly aircraft engines, produce oi. the plug is substantially completely illled.

such violent electrical disturbances that radio The use of an insulating sleeve constructed in reception and transmission have been found to the manner of the present invention provides be practically impossible. As a result therefore for an insulator whose dielectric strength is not of these disturbances proper shielding of the ail'ected by moisture, oils or changes in atmosignition leads, the magneto and spark plugs of pheric pressure, and if damaged in any way can the system are imperative tor the successful be ead y ep aced independently the 1 w functioning of the radio equipment. pl s- The use of shielding for the ignition cables, The provision oi insulating material in the prop ly grounded, and for the magnetos of the inner wall of the metallic sleeve makes the ignition system are known to be old in the art same practically airtight'by reason of the miniand form no part of the present invention. To mum of air space occurring between the inner be eflective the shield must, however, be conwall of the shield and the spark plug; therefore tinuous throughout the entire extent of the accumulation of moisture upon the insulated system including means for shielding the spark surface of the plug is substantially prevented.

plugs in order that the disturbances produced A furth obleet 0f -pr en inv t on is to by the spark discharge of the plugs may be conprovide in a metallic sleeve of this character 40 fined so that they produce no interference with Suitable coupling means comprising an insert o the radio equipment. a material having high electrical conductivity The main object therefore of the present infor effecting a good electric contact between the yention is to provide means for enclosing the conductor wire of the cable and the terminal end terminal portion of a spark plug to not only of the spark plug, particularly designed to efiecefiect an electric bond between the shielding of tlvely dissip the heat from e terminal end a shielded cable and the ground portion of a of the spark plug to the external shielding in spark plug, but also to completely insulate the order to keep the temperature of the conductor terminal portion of the spark plug and cable, wire adjacent the terminal of the spark plug at to confine the disturbances produced by the spark the minimum and prevent drying out and crack- 55* discharge of the plug and thereby form a coning of the insulation covering the wire.

tinuous shield the purpose of which is to preinsert is so constructed that diiiusion oi oi vent the emanation of any electromagnetic waves static stress over as great an area as 11!? into the atmosphere surrounding the plug as may be effected, thus decreasing there 55 well as the remainder of the ignition system. density at any one point to 1',

clrurge or" eossible end any tendency to breakdown of the gap and consequent flesh over to ground is substantially prevented.

s A still further object or? the present invention is to provide a. novel arrangement of parts so assembled as to retain the elements in their operative relation to one soother yet permitting their rileessccietlon for the purpose of cleenin 10 the spark plug, renewing worn or broken ports one the like.

Vitzi the sleeve end other objects in view, ch appear as the description prcceees, to invention resides the combination enel eoeemeut cl cool oeteils or construeerl hereinafter described and clulmerLit Icelrg ,uclerstcod time scope of whet elemeel changes the oreciee ct invention shown may "are made tritlzoutcle= re ting from the spirit or the luveut c c o culled fore: levy c3? slriele, oer j. 3 further mfimQfi deferring more particularly to the wherein corresponding ports ere designated by like riumerels throughout tire several views erect) to indicates e spark plug oi em arrovm moire, which comprises generally the eerie eorfico ll having e threaded portion at 5; end edeeteo for sttociumezot to the not shown) of so internal combustion engine, cool :1 core 12 that compr ses a or center electrcele is erirl irisuletlon materiel sum-omelet electrode. The outlet of selcl .eleetroele is provicleel with e.- reetsl disk or tesi'or electrical connection with the locus or ceele of the ignition system of? tloe crimes. 7

cable as is ioroviilecl with it mec that B electricellv grounded to the (not shown) lav means of a spec plug or need that is electrically connected st one cool to the metallic shield 21) and at its otli s coal to the tlireeeiezl portion 18 or the slug.

steers. slilelrl or laced comprises an outer metellic owns or covering, an inner sfceil oi insulation material in intimate contest with cuter shield and e oertitiou formed within e-limes end siuTteialv constructed to lee 'e i'lie cable insulation from the plug movies aeiiculeler e out 16 to oblv is; ool edeoteci to engage with tlireetleu portion of the spemplug. arrangement permits the metallic sleeve to he held in good electric contact 75: with the grounded geortion oi" the sporlugilug with the inner walls of the sleeve to provide for mszdmum heat conductivity to the suicl sleeve. 'Iioe insulating materiel is of sufflcient thickness pructlcellv fill the specs Zcetvveen the 11 eve snot the outer surface of the terminal gooeticri of the sperl: thereby meiictclu the same substantially i3. direct contact with soicl stu'iece.

'lliis construction permits s which is practically eirtigiit and iv reason of the very ll amount oi o see Iulci'l occur" Tee e of shield, so uletiug eur ending to foul the u eutlsllv pre= erl. materiel forming the outer-sleeve oi sufilcient thickness to eermit e. rigid corestruction end; imparts sufieicnt strength to the structure to enable the sleeve to Withstand cousitlereole rough treatment without d sturbing the proper functioning of the spark plug. It also sets es e. protection for the insulated ciicl o! the spark plug. lts overell dimension as to is sucit that it requires no additional space lll mounting the sport: plug on the engine.

Provision is made for suitably protecting the cable iusu etion so to prevent its deterioration by the heat witiuln the shielded specie. Ac-

cordingly en inclosure for the portion 02- a the cable lmuletiozi that is disposed within the shield-eel speri; plug is provided. to isolate the cable insulation from the spark plug center electrode. As illustseted in the several views of the drawing this inclosure is rormeci by providing it partition within the shielded sperl; plug. Verious means of incloslrag the end portion of the cable insulation will be obvious to those skilled in the art Without departing from the spirit or the invention. As illustrated in the several views of the drawing, the partition is formed by providing an insert 22 thet lies intimate surface contact with the Wall of the inner shell 19. This insert is preferebly made of steel encl'is provided with a central opening to receive e. closely fitting conductor part through which it is connected to the cable terminal. As shown in insert is connected the by the excel ends 23 of the celole conductor. As in i of and co stitutes the conductor nnect the re- 1e eieme t irsert.

b 5 er: Elli ccoropiisl'iezl es illustrated in r portions of the meteoric provide shoulder 24" The upper portion 19 saves as e spacer. Between 2 the inner sleeve and; the cleorsE upper connection 21 there is provided a. ferrule or washer is", which cooperates with the m detachable connection 26 and the insert to one sees: she in place As shown c, the end oi. the conductor wire is secured to the inner end of the coiled spring 25, which makes direct contact with the spark plug terminal'21, and by its spring action permits drawing down of the sleeve to make good electrical contact and .s tight joint at its junction with the grounded portion of the spark plug.

insert is so designed as to have as large ores possible, the sides of which are in contact with the inner surface of the 3229111 m t this manner the cable direct with the e eemter electrode end st sufficiently rapid t contact be hung I 1* I. as insert the 8A o seller which ewes oi the 2o.

m earls:

1 meeting with lei meloslng cable insulation to protect the against impairment by the nest within said plu 2. In a spark plug adapted to receive an insuleted cable, a metallic body shell, an electrode corn/mg core cilsposed'thereiza, a been having 51o electrode, said -.eac external meta shield l'or electrically ing with so; metallic body shell. and means for insulating said metallic the terminal of said core eectroele, said dlelee trio means including insulation material tlmate contact with ssld metallic body torming a closure with said conductor part i the cable insulation, said insulation rial conductor part serving to effectively e heat from within said plug to said sh vent deterioration of the insulation o and to prevent flash over between conductoz part. 3. A shield for spur plug tricolly connect the shielding of a mth sand Ly thin cross-section o: :1 wal s cable, an a "trlce ly comect the plug l and cooperating; with said serial to prevent deterioration of insulation is heat.

seer; slug adapted to elseermine-As sulstiou m o com for the ome shielding cured together near one ens of said plug, the shielding for the plug Sorming a part of the grounded portion of the plug, the insulation for the conductor of said cable extending wlthln the plug shielding, the terminal of said conduc- Jan. 22, 1935. R. DANUFF ET AL AUTOMATIC FILM CUING DEVICE Filed Oct. 13, 1933 2 Sheets-$heet 1 ATTORNEY g QMINVENTOR, 

